Temperature sensor with micro-ring assisted Mach-Zehnder filter

A temperature sensor with micro ring-assisted Mach-Zehnder filter is presented. It has a micron size. A micro-ring cavity is coupled in one of the arms of the Mach-Zehnder interferometer, in which some temperature-sensitive liquid is injected into the cavity by using the microfluidic technique. The temperature change can be detected by analyzing the output spectrum of the sensor. In order to achieve the good filtering performances, the arm-length difference of common MachZehnder filters is usually the order of millimeter. While the M-Z arm-length difference of the temperature sensor presented in this paper is only about 10um. The sensor has good filtering performances. Its extinction ratio is 10dB and the 3dB bandwidth is less than 1nm. In addition, the resolution of the temperature detection is 0.1°C. Moreover, the temperature detection range of the proposed sensor can be adjusted by changing the refractive index of liquid in the micro ring cavity.